The fight for the hearts, minds and votes of American Airlines Inc. mechanics is officially on.

The International Brotherhood of Teamsters announced Tuesday that it has collected signatures from more than 50 percent of the approximately 10,000 American Airlines mechanics and related employees asking for a representation vote.

It will face off against the two unions now representing those employees at American and American’s merger partner, US Airways Inc. — the Transport Workers Union at American and the International Association of Machinists and Aerospace Workers at US Airways.

The Teamsters filed a similar request May 7 to represent US Airways mechanics and related employees, replacing the IAM.

Tuesday morning, the Teamsters submitted its signature cards to the National Mediation Board, which will investigate and determine if the union presented enough “showing of interest” to justify a vote. The Teamsters need signatures from more than half the eligible employees.

Immediately after the filing, American mechanics and Teamsters officials held a Washington, D.C., news conference to announce the step — 11 months after the union began organizing efforts at American’s maintenance bases and line stations.

Teamsters officials and American mechanics who helped in the organizing effort took turns criticizing the TWU, which has represented American’s mechanics and related employees for decades.

They blasted the TWU for losses suffered by its members during American’s ongoing bankruptcy case, including agreeing to let more maintenance work be outsourced to places such as China.

“Today is a very happy and joyful event,” said Hank Rogish, a 22-year American employee who had worked at its Alliance maintenance base. “It’s also a day of relief and deliverance.”

He said he was speaking “for thousands of aircraft mechanics and facilities maintenance people all over the system from American Airlines who have been under the heavy hand of a tough employer and suffering from weak union representation. Today is a historic event where we’re going to get that changed and get that turned around.”

TWU members agreed to a concessionary contract with American as the airline sought to throw out its existing contract in bankruptcy court. The new contract, agreed to in August, imposed deeper cuts in jobs, working conditions, pay, benefits and job protections.

“This bankruptcy is no excuse for all the losses we’ve suffered at American,” 24-year employee Jim Witt, a Los Angeles-based mechanic, said.

The Teamsters announcement came two weeks after TWU and IAM officials announced they were forming a joint council to represent ground workers at the two airlines rather than fight each other to be the sole union.

After the Teamster news conference, TWU and IAM leadership attacked the Teamsters for job losses, concessions and outsourced work suffered by mechanics at airlines it has represented, particularly at United Airlines Inc.

Garry Drummond, director of TWU’s air transport division, called the Teamsters “a rogue union” that is losing members and is “raiding established unions” to replace members who are deserting it.

“The Teamsters are a troubled union. They are the only labor organization in the United States under federal oversight as a result of their extensive history of corrupt practices,” Drummond said in his statement.

IAM general vice president Sito Pantoja said the Teamsters “continue to destroy the labor movement by dividing already unionized employees with hollow promises. They are doing nothing to bring new airline workers into the labor movement. Instead, they try to siphon members from other unions, at the expense of those members and their families.”

Witt defended the campaign to bring in the Teamsters.

“Many people want to focus on the idea of unions fighting each other,” Witt said. “But that’s not what this campaign is about. It is about us. We are organizing to become Teamsters. … Let me emphasize — it was us who approached the Teamsters because our current union lacks the power we need to be heard.”

American carefully stayed out of the debate about which union should represents its mechanics.

“Our people have the right to union representation and to choose which union represents them,” American spokesman Paul Flaningan said. If the NMB authorizes an election, “we hope our mechanics will examine the options and take the time to vote on the path they believe is best for them, their families, and the company,” he said.